Abstract:
O fulereno (C60) pertence a uma família de nanomateriais (NM) constituída
exclusivamente de átomos de carbono, sendo encontrado na forma de suspensão na água
(nC60). A nanoprata (nAg) possui um excepcional e amplo espectro bactericida e um
custo de fabricação relativamente baixo. No entanto, pouco se sabe a respeito dos
eventuais efeitos tóxicos induzidos por estes NM em organismos estuarinos. O
poliqueto Laeonereis acuta tem o muco colonizado por comunidades bacterianas. Há
registros de que L. acuta apresenta um gradiente corporal para concentração de EAO e
capacidade antioxidante total. Neste estudo, os poliquetos foram expostos in vivo
durante 24 horas ao nC60 e à nAg, separadamente. Após isso, as unidades formadoras de
colônias (UFC) bacterianas foram contadas e pesadas, além de serem realizadas diversas
medições bioquímicas nos poliquetos e nas bactérias. Os números de UFC bacterianas
expostas ao nC60 foi menor na concentração de 0.01mg/L e os números de UFC
bacterianas expostas à nAg foram similares aos dados de biomassa, diminuindo na
maior concentração (1.0 mg/L) (p<0.05). A capacidade antioxidante contra radicais
peroxil em homogeneizados bacterianos expostos ao nC60 foi menor na concentração de
0.1mg/L quando comparado ao controle (p<0.05). A região anterior apresentou menor
capacidade antioxidante (p<0.05) nos poliquetos expostos a 1.0 mg/L, quando
comparado ao controle. Os poliquetos expostos à nAg apresentaram menor capacidade
antioxidante na região posterior na concentração de 1.0 mg/L quando comparado ao
controle (p<0.05). O conteúdo de peróxidos lipídicos (TBARS) foi reduzido na região
anterior dos poliquetos expostos nas duas menores concentrações ( 0.01 e 0.1 mg/L) de
nC60 (p<0.05). Na região corporal posterior, somente os organismos expostos a maior
concentração de nC60 (1.0 mg/L) mostraram aumento na concentração de TBARS
quando comparado ao grupo controle (p<0.05). A atividade da enzima glutationa-Stransferase
(GST) foi aumentada (p<0.05) na região média e posterior dos poliquetos
expostos a 0.1 mg/L de nC60. Como conclusões pode se dizer que os dois NM
induziram efeitos tóxicos ainda numa situação (escuridão) onde o fulereno não é fotoexcitado.
O aumento na produção e comercialização de produtos com NM levanta a
questão dos riscos ambientais associados ao desenvolvimento da nanotecnologia.
Fullerenes (C60) are a family of NM constituted exclusively by carbon atoms. The most
environmentally relevant form of C60 is the fullerene water suspension (nC60). nAg
posses an exceptional broad spectrum bactericidal activity and relatively low cost of
manufacturing. The polychaete Laeonereis acuta has the mucus colonized by bacteria.
There are reports that ROS concentration and total antioxidant capacity showed a body
gradient in L. acuta. The worms were exposed during 24 hours to nC60 and nAg. After
this, the bacterial CFU were counted and weight. Biochemical analysis polychaetes and
bacterial samples were made. The number of bacterial CFUs exposed to nC60 was lower
in the concentration of 0.01mg/L and the number of bacterial CFUs exposed to nAg
were similar to weight data, since decreased at the higher concentration (1.0 mg/L), in
relation to the other concentrations and control (p<0.05). Antioxidant capacity against
peroxyl radicals in homogenates of bacterial exposed to nC60 was lower in the
concentration of 0.1mg/L when compared to the control (p<0.05).The anterior region
presented lower antioxidant capacity (p<0.05) in worms exposed to 1.0 mg/L, when
compared to the control. Worms exposed to nAg presented lower antioxidant capacity
in the posterior region of those exposed to 1.0 mg/L when compared to the control
(p<0.05). Lipid peroxides content was reduced in the anterior region of worms exposed
to the two highest concentrations (0.1 and 1.0 mg/L) of nC60 (p<0.05). In the posterior
body region, only worms exposed to the highest nC60 concentration (1.0 mg/L) showed
augmented TBARS concentration when compared with the control group (p<0.05). The
activity of GST revealed to be augmented (p<0.05) in the middle and posterior region of
worms exposed to 0.1 mg/L of nC60. As conclusions, can be said that the two NM
induced toxics effects even in a situation (darkness) where the fullerene is not photoexcited.
The increase in production and marketing of products with NM raises the
question of the risks associated with the development of nanotechnology.
Fullerene (nC60) and nanosilver (nAg) are nanomaterials with bactericide properties.
The increments in their use raise questions about their potential environmental impacts,
including estuarine ones. The polychaete Laeonereis acuta (Nereididae) secretes mucus
that is colonized by bacteria communities. We analyzed the biochemical responses of
anterior, middle and posterior region of L. acuta and bacteria communities after nC60 or
nAg exposure during 24 h. Molecular analysis showed a prevalence of Vibrio genera in
the communities. Bacteria biomass was lowered in worms exposed to 1.0 mg/L of nAg.
nC60 reduced total antioxidant capacity of bacteria from worms exposed to 0.1 mg/L.
Worms anterior region presented lower antioxidant capacity after exposure to 1.0 mg
nC60/L, and the same was observed in the posterior region of worms exposed to 1.0 mg
nAg/L. Lipid peroxidation was reduced in the anterior region of worms exposed to nC60
and the opposite was observed in the posterior region.
